Nociception is enhanced after low doses and reduced after high doses of the serotonin receptor agonist 5-methoxy-N,N-dimethyltryptamine.
Neuroscience letters – September 01, 1980
Source: PubMed
Summary
Intracerebroventricular injections of 5-methoxy-N,N-dimethyltryptamine significantly altered pain sensitivity. At doses of 1.6 to 25 micrograms (n = 8 for each), tail-flick latencies decreased by 13-24%. Notably, 50 and 100 micrograms produced a biphasic response, initially increasing pain sensitivity before inducing relief. In contrast, a higher dose of 400 micrograms led to a 28-39% increase in latency, suggesting that lower doses may diminish serotonergic neuron activity while higher doses stimulate spinal receptors for pain relief.
Abstract
The effects on pain sensitivity of intracerebroventricular injections of 5-methoxy-N,N-dimethyltryptamine were tested by the tail-flick method. Following administration of 1.6, 3.1, 6.3, 12.5 and 25 micrograms (n = 8 for each dose), tail-flick latencies were reduced by 13-24%. Fifty and 100 micrograms caused a biphasic response (hyperalgesia followed by analgesia), whereas 400 micrograms increased mean latencies by 28-39%. The hyperalgesia observed after low doses was most likely due to reduced activity in descending serotonergic neurons following presynaptic stimulation. Higher doses caused analgesia, probably by stimulating spinal postsynaptic serotonergic receptors as well.